One of the most prominent Muslim scholars and scientists of the medieval era, Nasir al-Din Tus i (1201-1274) joined the Shi'i Nizari Ismaili community at an early age, soon after completing his education. In the course of his long and distinguished career, first under the patronage of the Ismailis at their fortresses in Persia and subsequently with the conquering Mongols, he produced over 150 works on a variety of subjects, from theology and philosophy to mathematics and astronomy. His principal works on Nizari Ismaili doctrine, the Rawda-yi taslim (Paradise of Submission) and the autobiographical Sayr wa suluk (Contemplation and Action), are already available in English translation by S. J. Badakhchani, who in this volume brings together new critical editions and translations of three shorter Ismaili works by Tusi, namely Tawallawa tabarra (Solidarity and Dissociation), Matlubal-mu'minin (Desideratum of the Faithful) and Aghaz wa anjam (Origin and Destination). In these three treatises, Tusi provides concise interpretations of key motifs in Ismaili doctrine, with special reference to the primordial nature of man, his earthly existence in relation to the Imam, and his destiny in the hereafter.